Phalenopsis orchid leaves with black patches

[sweta]

Hello Orchid Pals,

I bought this orchid on clearance couple of days ago and it didnt seem to have any issue. Probably just one small black spot that I didnt think could turn out to be an issue. But now I see that it seems to be spreading and looks like some bacterial or fungal issue. Please suggest ways I can give the right treatment for it. Right now it sits on a window sill and house temperatures are around 70F and humidity 40%. One more thing to mention is it had decorative spanish moss at the top which could have contributed to more humidity. I removed the moss 3 days ago.

Pictures are attached.

Thanks,
Swetha